Watch Where You Point That Thing: Understanding Focus Points and How to Use Them

Oftentimes with older film cameras, images ended up out of focus (or in technical camera terms, “fuzzy”). This was because we needed to rotate the lens to get the sharpest photo. But all of that is in the past, right? Those of us with the more expensive digital cameras (like DSLRs) know that this is not the case. This is due to two factors – one is called “depth of field” (DOF) and the second is called “focus points.”

These photos were both taken with a wide aperture (f-stop = 3.5) setting. When an object in the foreground is focused on, everything else is blurry. The same thing happens when the focus is on an object in the background.

Depth of field (DOF) is really just the amount of the image that is in focus. Directly connected to the f-stop, DOF will be different depending on the f-stop, or aperture, that the camera is set at. These are those numbers like f 2.8, f 5.6, and f 11. For photography, the higher the f-stop number, the narrower the DOF and the more of the image will seem sharp and in focus.

Here is the same photo taken with a narrow aperture setting (f-stop = 13). You can see that everything is now in focus.

However, this is also dependent on how much light is shining on the objects in view. Bright sunny days will give us f-stops of f 8 or higher, which means pretty much everything is in focus. We only get into trouble when the light level drops like early morning, evening, shady areas and inside. Then we will see the f-stop drop down to f 5.6 or lower, giving us a wider DOF and more problems with focus. This is when we have to be more concerned with the second part of this equation, which are those focus points.

Focus points are those little squares we see through the viewfinder that light up. For some of the more simple cameras, there may only be one or three points near the center of the viewfinder. If you make sure that the center point is always on your subject, you will be okay. However, if you have two people in the frame and a gap between them where the center focus lines up in that gap, you may end up with a very sharp image of the Rocky Mountains behind them and couple of soft fuzzy people. If you can’t get them to move closer together, try this trick:

Move the camera right or left until your center focus point is on someone.

Then, hold the shutter button down halfway until the lights in the viewfinder turn on.

Without releasing the shutter button, move the camera back.

Press the shutter the rest of the way for the image. The camera will hold the focus so long as you don’t release the button (the camera will try to refocus again if you let go of the shutter button).

Some of the more expensive DSLR cameras can even track your eye as it looks around the viewfinder to find a different focus point. This is when some of those other red boxes start to light up. Any box that is red shows that the camera is focusing on that point of the image. You can even go manual and pick different focus points so that you won’t have to worry about where the camera thinks you want to focus on. A very handy feature if you have something close to you that you don’t want to have sharp and in focus.

If all of this seems more trouble than it’s worth, take heart. You can always go back to the manual focus. On the lens you will see a switch for AF / MF. Click it to MF and you will have only yourself to blame for out of focus photos.

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4 Comments

01-08-2012

Paul says:

Hello. I have a question. I own a Nikon D300S. I’m taking pictures of couples jus to practice the focusing techniques, but I am havin trouble getting the two subject into focus and the background blurry. I always end up with one person in focus and the other one blurry or fuzzy :). How should I set up my camera if I’m shooting outdoor with some sun light, around 6, 7 pm Denver time? Thank you for the help.

Thank you for your question. Ideally, you will want to set up your camera to have a narrow depth-of-field (DOF), and try to have a good amount of sunlight in your shots.

As it states in the article, the higher the f-stop number, the narrower the DOF and the more of the image will seem sharp and in focus. Play around with your f-stop settings in the high number range and see if that helps you keep both subjects in focus.

In low light settings, you’ll need to play with your focus points. Try the focus point tips stated above in the article to “set” your camera’s focus points for each individual photo. This way you can focus on one individual, hold the shutter button halfway down, and move the camera to include both individuals that you’re trying to shoot.

This kind of stuff takes practice and patience, and depends largely on your individual camera’s abilities. If you’re in the area, our Intro to DSLR course covers this topic in detail.

When photographing people is can be hard to get both in focus while still getting that soft blurry background. The depth of field or how much is in focus can depend on not just the f stop you are using but the lens. A longer lens like a 120mm or longer can give you a very short depth of field even at f stops like f 4 that will get both heads in focus. One other thing you can do is focus on the eyes and not the nose. Of course you can always have your couple move closer together so that their heads will be on the same plane and within the Depth of field.